Wireless access systems have been widely deployed to provide various types of communication services such as voice or data. In general, a wireless access system is a multiple access system that supports communication of multiple users by sharing available system resources (a bandwidth, transmission power, etc.) among them. For example, multiple access systems include a Code Division Multiple Access (CDMA) system, a Frequency Division Multiple Access (FDMA) system, a Time Division Multiple Access (TDMA) system, an Orthogonal Frequency Division Multiple Access (OFDMA) system, and a Single Carrier Frequency Division Multiple Access (SC-FDMA) system.
That is, in legacy wireless access systems, a Base Station (BS) or a UE performs communication using a Half Duplex Radio (HDR) scheme of a Frequency Division Duplex (FDD) scheme for transmitting signals on a wireless resource divided based on frequency or a Time Division Duplex (TDD) scheme for transmitting signals on a wireless resource divided based on time.
However, in the HDR communication scheme, the UE and/or the BS are incapable of simultaneously performing reception and transmission in the same frequency/time resource. Therefore, introduction of an FDR communication scheme has been proposed to efficiently use resources. The FDR communication scheme refers to a scheme in which the BS and/or the UE simultaneously transmit and receive different signals in the same frequency/time resource zone.
Notably, since the BS and/or the UE simultaneously perform data transmission and reception through the same resource zone in a communication environment of the FDR scheme, self-interference in which a signal transmitted by the BS or the UE is received through a reception antenna of the BS or the UE occurs. In addition, mutual interference may occur when both an FDR zone and an HDR zone are configured together.
Accordingly, the methods for measuring self-interference channels are needed to reduce self-interference in a wireless access system supporting FDR scheme.